1. Field of the Invention
The present invention relates to an element whose focus is electrically tunable, particularly to a liquid crystal lens whose refractive index is electrically tunable.
2. Description of the Related Art
With development of optical imaging technology, liquid crystal (LC) lenses are widely used in various imaging devices, such as electrically tunable glasses, cameras, projectors, and endoscopes. The conventional LC lens normally contains only a single LC unit, and the lens effect is achieved via the electrode design or thickness variation of the single LC unit. However, these technologies still have some limitations, which is why manufacturers are continually striving to develop improved design.